In general, a clothes dryer is a device that absorbs moisture from objects to be dried (load) by blowing hot air generated by a heater into a drum and thereby dries the load. Clothes dryers may be roughly categorized into an exhaust type clothes dryer and a condensation type clothes dryer, according to the method employed for handling the humid air occurring when absorbing the moisture and drying the load.
The exhaust type clothes dryer employs a method for exhausting the humid air flowing from the drum to the outside of the dryer. However, it requires an exhaust duct for exhausting the moisture evaporated in the drum to the outside. In particular, when gas heating is employed, the exhaust duct needs to be installed being extended long enough to the outdoors, considering that carbon monoxide, etc. as a product of combustion are also exhausted.
Meanwhile, the condensation type clothes dryer uses a recirculation method that removes moisture by condensing the moisture from the humid air flowing from the drum in a heat exchanger and then re-circulates the moisture-removed dry air back into the drum. However, the drying air flow forms a closed loop, making it difficult to use gas as a heating source.
A ductless dryer overcomes the demerits of the exhaust type dryer and the condensation type dryer. That is, the ductless dryer can be maintained at a low cost by using gas as the heating source and does not require an additional exhaust duct to be extended to the outdoors.
Meanwhile, the heat exchanger in the conventional condensation type clothes dryer is generally an air-cooled heat exchanger, thereby being unable to fully condense moisture contained in gas supplied from the drum up to a required level. Accordingly, the moisture would be introduced back into the drum through the heat exchanger or be greatly contained in gas exhausted to the outside.